Transcript TOXICOLOGY - Pacific Lutheran University

TOXICOLOGY –
The study of poisons
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Materia Medica – poisons classification
- Dioscorides
Court of Nero, 50 AD
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“The dose makes the poison”
- Paracelsus
16th century German physician
Scope of the Problem
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Reagents can represent a toxicity hazard to
students and instructor.
Protection of students and staff is important.
Most common sources of contamination
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Pipetting by mouth
Eating with contaminated hands
Drinking from contaminated containers
Applying contaminated make-up
EFFECTS OF TOXIC
CHEMICALS
Structural Differences are very
important:
For example, two closely related PCB’s
Basic Considerations
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Dose
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Length of Exposure
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Organs or systems on which the
chemicals have an effect
Dose-Response Relationships
Hyposensitive
N
o
r
m Normal
a
l
Hypersensitive
Dose Response Relationship
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Dose make the poison
Dose units provide toxicity
measurements
Major response terms for toxic or lethal:
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Toxic concentration:
Toxic dosage:
Lethal concentration:
Lethal dosage:
TC
TD
LC
LD
Toxicity may be different in different
species:
Most Common Routes of Entry
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Oral
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Inhalation
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Gastrointestinal tract exposure
Respiratory tract exposure
Pericutaneous
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Through the skin, a dermal or epidermal
exposure
Major Sites of Exposure, Metabolism,
Storage and Excretion
Local and Systemic Effects
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Local Effect
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Occurs directly where the chemical
contacts the body
Systemic Effect
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Caused when a toxic reagent is absorbed
and circulated by the blood to systems and
organs that can be effected by the toxin
Effects may be lessened by the body’s
ability to detoxify and eliminate the toxin
Acute and Chronic Effects
A. Acute exposure
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Single or short-term exposure
May have sudden onset of affect and a
short duration
Some short term exposure may cause:
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Permanent adverse effects
Delayed effects
Chronic effects
Acute and Chronic Effects
Continued
B. Chronic exposure and effects
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Repeated or prolonged exposure to low
concentrations of toxic chemicals
Chronic effects are:
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Of long duration
Frequently recurring
Slowly progressing in seriousness
c. Similar exposure to some toxins will
have effects that stop when exposure
stops
General Classes of Effects
A. Immune suppression
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t-cells
t-cells
B. Central nervous system effect
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CNS is most sensitive to adverse changes in brain function
or nerve conditions
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Drugs: designer drugs, phenobarbitol, narcotics
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Solvents: toluene, styrene, xylene, methyl ethyl ketone
General Classes of Effects
Continued
C. Carcinogenic
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Uncontrolled growth of genetically-controlled
cells
Multi-stage theory
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Initiation
Promotion
Progression
D. Tetratogenesis – changes in embryos
Effects on Life Processes
A. Exposure of an individual to a toxic substance
may alter one or more basic life processes,
including:
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2.
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6.
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Irritability – ability to respond to stimulus
Conductivity – nerve impulses
Contractility – ability to change form by
shortening
Metabolism
Integration – ability to coordinate activities by
acceleration or deceleration or activities
Adaptation
Reproduction – ability to repair and reproduce
Effects on Life Processes
Continued
B. System toxic effects are often first
recognized as shift in physiological or
behavioral patterns
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Shift may be subtle or dramatic
Toxicology Management
A. Risk vs. Benefit
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Least-toxic reagents
Alternate procedures
Simulations
B. Voluntary vs. Involuntary Risk
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Instructor
Student
Experienced research scientist
Toxicology Management
Continued
C. Setting Standards
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OSHA
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Chemical hygiene plan
“Right to Know” law
Disposal regulations
NIOSH
D. Sensitive Sub-Populations
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Pregnant females
Allergic reactors
Toxicology Databases
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Toxnet – National Library of Medicine
http://toxnet.nlm.nih.gov/
Databases on toxicology, hazardous chemicals, environmental health, and
toxic releases
Toxicology tutorial
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Amer. Assn. of Poison Control Centers
http://www.aapcc.org/
OSU Community Outreach and Education Program
Classroom activities and labs - toxicology
http://www.hydroville.org